Centrifugal casting devices

ABSTRACT

Centrifugal casting device, notably for tubular pieces without longitudinal draw, by means of half-moulds kept in their assembled condition during the casting operation in a centrifugal casting cylinder, with the assistance of a number of inertia weights and levers acting upon said half-moulds, said inertiaweights being pivoted to brackets rigid with said centrifugal cylinder through the medium of crank levers having unequal arms, the major arms of said levers being rigid with said inertia weights and extending through openings formed in said centrifugal cylinder, the minor arms ending with rollers bearing upon said half-moulds.

United States Patent [1 1 Peltier et a1.

[ 1 Jan. 16,1973

[54] CENTRIFUGAL CASTING DEVICES [75] Inventors: Henri Peltier; Roger Bailly; Pierre Chatourel, all of Billancourt, France [73] Assignees: Regie Nationale Des Usines Renault, Billancourt; Automobiles Peugeot, Paris, France 221 Filed: Aug. 16,1971

211 Appl.No.: 172,005

[30] Foreign Application Priority Data Sept. 8, 1970 France ..7032600 [52] 11.8. C1 .L ..l64/293 [51] Int. Cl. ..B22d 13/10 [58] Field of Search ..l64/293, 292, 287

[56] References Cited UNITED STATES PATENTS 2,727,288 12/1955 Saives ..164/293 FOREIGN PATENTS OR APPLICATIONS 117,543 7/1918 Great Britain ..164/293 Primary Examiner-Robert D. Baldwin Att0rney-Stevens, Davis, Miller & Mosher [57] I ABSTRACT Centrifugal casting device, notably for tubular pieces without longitudinal draw, by means of half-moulds kept in their assembled condition during the casting operation in a centrifugal casting cylinder, with the assistance of a number of inertia weights and levers acting upon said half-moulds, said inertia-weights being pivoted to brackets rigid with said centrifugal cylinder through the medium of crank levers having unequal arms, the major arms of said levers being rigid with said inertia weights and extending through openings formed in said centrifugal cylinder, the minor arms ending with rollers bearing upon said halfmoulds.

9 Claims, 7 Drawing Figures PATENTEDJAN 16 I975 SHEET 1 [IF 2 PATENTEDJAN 16 ms sum 2 [IF 2 CENTRIFUGAL CASTING DEVICES The present invention relates to a centrifugal casting device applicable notably to the casting of pieces in metal chilled half-moulds, these pieces having no continuous draw in their longitudinal direction, such as detachable engine cylinder liners or other cylinders for miscellaneous applications.

Apparatus for centrifugal casting processes which utilize chilled halfmoulds kept in rigidly assembled condition during the casting operation are already known. These half-moulds are thus kept in their assembled condition in spite of the clearance existing between a centrifugal cylindrical frame structure and these half-moulds, by means of a number of inertia weights and levers acting upon the half-moulds in order to balance the effects of expansion and centrifugal force on the half-moulds and the metal cast therein, said inertia weights being pivoted to bracket means rigid with the centrifugal cylindrical frame structure and forming a rigid assembly with relatively obtuse arms extending through openings formed in said cylindrical frame structure and having their small sides provided at their free ends with rollers adapted to engage said half-moulds.

However, these various known devices are ill suited for providing a satisfactory solution to the problem of the wall concentricity of the moulded tube walls. Under these conditions, an extra thickness of the moulded tube walls (which is lost, of course, during the subsequent machining operation) had to be provided in order to preserve the prescribed dimensions.

In fact the aforesaid inertia weights and levers actually ensure a proper mutual engagement of the halfmoulds, but without properly centering them. However, these inertia weights cannot be considered as constituting self-centering elements, since the one remotest from the axis of rotation tends increasingly to move away from said axis as a consequence of the centrifugal force and to draw the opposite inertia weight towards the axis, as this last-mentioned inertia weight is increasingly unable to overcome the eccentric force exerted by the first inertia weight. The balance position of the two half-moulds lies intermediate the ideal position and the position of engagement between an external generatrix and a generatrix of the inner bore of the centrifugal cylinder.

Secondly, since the centrifugal cylinder or mould carrier is independent, a relative great number of these cylinders or carriers must be provided to ensure a satisfactory operation of an installation utilizing a number of these devices on transport means such as a turret or like carrier structure.

Moreover, the operation of the centrifugal cylinder or mould carrier is rather noisy during the centrifugation process, due to the rolling engagement of its circular rims with the driving rollers.

Finally, the turret proper constitutes a relatively heavy structure and the centrifugal cylinders proper have a certain inertia interfering with the starting of their rotational movement.

It is the essential object of this invention to provide a satisfactory solution of the various problems set forth hereinabove.

To this end, the centrifugal cylinder according to this invention comprises a cylindrical frame structure rigid with the driving device and half-moulds, and lever arms forming a certain angle to each other, the apex of this angle being pivoted to the centrifugal cylinder in the vicinity of the half-moulds, in order automatically and dynamically to center the assembled half-moulds. means being further provided for pennitting a proper adjustment of the moulded tubes bores.

Under these conditions, the inertia weights exert a substantially perfect centering action as will be explained presently. According to a specific form of embodiment of the invention, this arm angle is about 30. Advantageously, the rollers engaging said half-moulds are mounted on said crank levers with the interposition of needle bearings.

Other features and advantages of this invention will appear as the following description proceeds with reference to the attached drawing illustrating diagrammatically by way of example a typical form of embodiment of the invention. In the drawing:

FIG. 1 is a diagrammatic axial section showing the assembly of the centrifugal casting machine with its driving motor;

FIG. 2 is a cross sectional view taken along the line II-II of FIG. 1',

FIG. 3 is an axial section showing on a larger scale two half-moulds in their assembled condition;

FIG. 4 is a side elevational view of the assembly shown in FIG. 3;

FIG. 5 is a diagrammatic view showing on a larger scale a lever carrying an inertia weight and a roller, and

FIGS. 6 and 7 are diagrammatic views affording a clearer understanding of the mode of operation of the inertia weights.

Referring first to FIGS. 1 and 2, it will be seen that the centrifugal casting machine comprises a pair of half-moulds l, 2 assembled along a broken joint 3, 4. The bore 5 of these half-moulds corresponds to the outer diameter of the liners to be cast, and their length permits of casting tubes 29 to be subsequently cut into a number of separate liners, for example four in the case illustrated in FIG. 3 showing details of the halfmoulds.

At one end, for example, the right-hand end as seen in FIG. 1, i.e., the end opposite to the casting opening 6, the assembled half-moulds comprise an internal circular groove 7 adapted to retain in position a deflection washer 8 for separating the cast tube of four liners 29 from the excess molten metal collected in an end chamber 9, also referred to as the overflow chamber, communicating with the outside through the bore 10.

The function of the deflection washer 8 is to adjust, by means of its bore 11, the inner diameter of the cast tube; its low thermal inertia prevents the adjacent parts from hardening. Moreover, when opening the mould, it assists in readily separating, detaching or stripping the tube 29 (to be subsequently cut into liners) from the end riser having set in the overflow chamber 9. It may be remarked that this deflection washer 8 of relatively thin sheet metal is cheaper than the conventional sans deflection cores. Preferably, this washer is provided with a reinforcing rib (not shown).

As will be readily understood from the foregoing the function of overflow chamber 9 is to. collect the excess molten metal.

The outer portion of half-moulds 1, 2 illustrated in FIG. 4 does not form a continuous cylinder but comprises in the selected example four flat faces 12 adapted to be engaged by rollers as will be explained presently.

The assembled half-moulds 1, 2 are slidably engaged in the axial direction and with a certain clearance into the inner space of a cylindrical frame structure or centrifugal barrel 13, as illustrated in FIG. 1.

This barrel is a light-weight construction assisting in reducing the total weight or inertia of the structures or turrets supporting it. It comprises four identical anglesections 14 of a length corresponding substantially to that of said half-moulds 1 and 2; these angle-sections are disposed on the sides of a square, with their apices directed towards the axis of rotation X-X' of the halfmoulds. The angle-sections 14 are rigidly assembled by means of a number of steel rings 15. The wings of angle-sections 14 are also useful in that they produce a certain ventilation. A balancing device of a type known per se and comprising a ball ring 16 surrounds the cylindrical structure thus constructed.

The centrifugal cylindrical frame structure 13 is rotatably driven from a transmission system comprising for example a belt 17 disposed between the pulley 18 of a motor 19 and another pulley 20 of a ventilated adjustable friction coupling 21.

The assembly comprising said cylindrical frame structure 13 and its driving means is connected to a fixed structure 22 or to a turret via elastic suspension means 23 having an oscillation frequency definitely lower than the rotational speed of centrifugal barrel l3.

Shafts 24 supporting crank levers 25 are mounted at right angles to the wings of said angle sections 14. Each shaft 24 extends through one point of the apex of the acute angle formed by the crank lever 25. The arms of each lever 25 have unequal lengths, the longer arm 25,, supporting an inertia weight 26 and the shorter one 25,, the shaft 27 of a cylindrical roller 28 bearing on one of the flat outer faces 12 of said half-moulds l and 2. FIG. illustrates diagrammatically a lever 25 with its inertia weight 26 and a roller 28.

According to a preferred form of embodiment, the crank lever 25 is doubled in order to constitute a strap straddling the inertia weight 26 and roller 28.

According to another preferred form of embodiment, the roller 28 is mounted on the crank lever or in the strap formed by a pair of crank levers 25 via a needle bearing in order to prevent the half-moulds from being wedged against the rollers 28 when they emerge from the barrel l3.

The levers 25 supporting the inertia weights 26 and rollers 28 are disposed about the half-moulds by groups, each group comprising four such levers. One group is located substantially in the vicinity of the middle of said half-moulds and the other two are disposed the one at the front and the other at the rear.

The above-described device operates as follows:

The half-moulds I, 2 are assembled, previous insertion of the deflection washer 8 into groove 7. Then the tubular mould thus formed is introduced into the barrel I3 and the motor 19 is started. Due to the provision of variable friction coupling 21 the motor 19 is protected against overheating likely to result from the starting of an assembly having a relatively great inertia.

As the assembly begins to rotate, the action exerted by the centrifugal force on the inertia weights 26 causes them to pivot about the shafts 24 and the rollers 28 tend to move towards the axis of rotation and to press the two half-moulds 1, 2 against each other while permitting their thermal expansion and their proper longitudinal positioning.

During the rotationof the tubular mould consisting of the two halves 1, 2, the molten metal is cast and the centrifugal force presses this molten metal against the inner wall of the mould; the metal subsequently sets and the thickness of the cast liners is adjusted simply by the inner diameter of the deflection washer 8.

FIGS. 6 and 7 afford a clearer understanding of the improvement brought by this invention in the inertia weight operation.

In FIG. 6, showing a known system, during the rotation one of the inertia weight, such as inertia weight M pivoted at O and responsive to the centrifugal force F, takes a certain lead on the second inertia weight M pivoted at O and responsive to the centrifugal force P, so as to press the roller G with greater force against the half-mould l. The opposite weight M being unable to react, the inertia weight M remotest from the axis of rotation exerts a higher torque than inertia weight M. Under these conditions, it is clear that any more and more accurate adjustment of the relative spacing of said inertia weights, causing an accurate centering of the half-mould assembly 1, 2 on the axis of rotation X-X', is definitely precluded.

In FIG. 7 illustrating the arrangement of this invention, it will be seen that as the inertia weight M, fulcrumed at O diverges as a consequence of the centrifugal force F,, the torque F decreases. As a result, the action of roller G on half-mould 1 becomes inferior to that of roller G' on half-mould 2.

In the case illustrated in FIG. 6 (prior art), it was obviously hardly possible to reach a state of balance permitting a coincidence between the axis of rotation X-X' and the geometrical axis of the two half-moulds. In the case illustrated in FIG. 7, the stress reversal effect just described is capable of leading to the desired state of balance, thus ensuring a perfect concentric relationship between the inner and outer walls of the liners to be cast.

The centrifugal device described hereinabove comprises means for locking the joint plane 3-4 of halfmoulds l, 2 in the proper horizontal position as required for facilitating the opening of the mould halves during the stripping operation.

These means may comprise for instance a disk rigid with the shaft of the centrifugal frame structure and having at least one suitably positioned notch adapted to coact with a companion pin responsive to suitable control means (not shown).

At the end of the centrifugal casting operation the driving motor is operated in the opposite direction but at low speed until this pin stops the rotation of the motor and frame assembly, so that the joint is disposed horizontally.

Although a specific form of embodiment has been described and illustrated herein, it will be readily understood by those conversant with the art that various modifications in the details of parts and also in their relative arrangement and proportions may be brought without departing from the basic principle of the invention as set forth in the appended claims.

What is claimed as new is:

l. Centrifugal casting device, notably for tubular pieces without longitudinal draw, including halfmoulds kept in their assembled condition during the casting operation in a centrifugal casting cylinder with the assistance of a number of inertia weights and levers acting upon said half-moulds, said inertia-weights being pivoted to brackets rigid with said centrifugal cylinder through the medium of crank levers having unequal arms, the major arms of said levers being rigid with said inertia weights and extending through openings formed in said centrifugal cylinder, the minor arms ending with rollers bearing upon said half-moulds, this device being characterized in that said centrifugal cylinder comprises a cylindrical frame structure rigid with the driving device and the half-moulds, the arms of said levers forming with each other an acute angle having its apex pivoted to the centrifugal cylinder in the vicinity of said half-moulds, in order automatically and dynamically to center said assembled half-moulds, means being also provided for adjusting the bore of the moulded tubes.

2. Centrifugal casting device according to claim 1, characterized in that the value of said angle formed by the arms of said levers is about 30.

3. Centrifugal casting device according to claim 1, characterized in that said rollers are rotatably mounted on said crank levers by means of needle bearings in order to prevent the jamming of said rollers on said half-moulds when the latter are removed from said cylindrical frame structure.

4. Centrifugal casting device according to claim 2, characterized in that said rollers are cylindrical and c0- act with longitudinal flat faces formed to this end on the outer periphery of said half-moulds.

5. Centrifugal casting device according to claim 1, characterized in that said centrifugal cylindrical frame structure constitutes a light-weight assembly comprising four angle sections disposed on the four sides of a square with their corners directed towards the axis of rotation, said angle sections being rigidly assembled by a number of steel rings surrounding them.

6. Centrifugal casting device according to claim 1, characterized in that the centrifugal frame structure comprises a ball-type balancing device and is connected to a frame or turret through the medium of an elastic suspension system having an oscillation frequency definitely lower than the velocity of rotation of said cylindrical frame structure.

7. Centrifugal casting device according to claim 1, characterized in that the device driving the cylindrical centrifugal device comprises an adjustable friction coupling adapted to absorb the starting and stopping jerks, so as to protect the driving motor.

8. Centrifugal casting device according to claim 1, characterized in that the two half-moulds comprise an overflow chamber adapted to receive the excess molten metal fed to the mould assembly, said chamber being separated from the remaining portion of the bore of said halfmoulds by a detachable deflection washer of relatively thin sheet metal, retained in position by a circular groove formed within said half-moulds.

9. Centrifugal casting device according to claim 1, characterized in that locking and positioning means are provided for bringing the horizontal joint plane of the mould in a horizontal position at the end of a centrifugal casting operation. 

1. Centrifugal casting device, notably for tubular pieces without longitudinal draw, including half-moulds kept in their assembled condition during the casting operation in a centrifugal casting cylinder with the assistance of a number of inertia weights and levers acting upon said half-moulds, said inertiaweights being pivoted to brackets rigid with said centrifugal cylinder through the medium of crank levers having unequal arms, the major arms of said levers being rigid with said inertia weights and extending through openings formed in said centrifugal cylinder, the minor arms ending with rollers bearing upon said half-moulds, this device being characterized in that said centrifugal cylinder comprises a cylindrical frame structure rigid with the driving device and the half-moulds, the arms of said levers forming with each other an acute angle having its apex pivoted to the centrifugal cylinder in the vicinity of said half-moulds, in order automatically and dynamically to center said assembled half-moulds, means being also provided for adjusting the bore of the moulded tubes.
 2. Centrifugal casting device according to claim 1, characterized in that the value of said angle formed by the arms of said levers is about 30* .
 3. Centrifugal casting device according to claim 1, characterized in that said rollers are rotatably mounted on said crank levers by means of neeDle bearings in order to prevent the jamming of said rollers on said half-moulds when the latter are removed from said cylindrical frame structure.
 4. Centrifugal casting device according to claim 2, characterized in that said rollers are cylindrical and co-act with longitudinal flat faces formed to this end on the outer periphery of said half-moulds.
 5. Centrifugal casting device according to claim 1, characterized in that said centrifugal cylindrical frame structure constitutes a light-weight assembly comprising four angle sections disposed on the four sides of a square with their corners directed towards the axis of rotation, said angle sections being rigidly assembled by a number of steel rings surrounding them.
 6. Centrifugal casting device according to claim 1, characterized in that the centrifugal frame structure comprises a ball-type balancing device and is connected to a frame or turret through the medium of an elastic suspension system having an oscillation frequency definitely lower than the velocity of rotation of said cylindrical frame structure.
 7. Centrifugal casting device according to claim 1, characterized in that the device driving the cylindrical centrifugal device comprises an adjustable friction coupling adapted to absorb the starting and stopping jerks, so as to protect the driving motor.
 8. Centrifugal casting device according to claim 1, characterized in that the two half-moulds comprise an overflow chamber adapted to receive the excess molten metal fed to the mould assembly, said chamber being separated from the remaining portion of the bore of said half-moulds by a detachable deflection washer of relatively thin sheet metal, retained in position by a circular groove formed within said half-moulds.
 9. Centrifugal casting device according to claim 1, characterized in that locking and positioning means are provided for bringing the horizontal joint plane of the mould in a horizontal position at the end of a centrifugal casting operation. 